Bare soil evaporation under high evaporation demand: a proposed modification to the FAO-56 model

Torres, Emy Shilena; Calera, Alfonso

doi:10.1080/02626661003683249

Cited by 48 publications

(33 citation statements)

References 23 publications

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“…This value was not included in the NIWR since the irrigation frequency and doses must be considered unknown in real-time applications, providing irrigation advice a week ahead. In addition, several authors were alerted about the partitioning between crop transpiration and soil evaporation based on the FAO-56 approach since the Kcb-NDVI relationship already includes a residual soil evaporation [29], and the depth of the evaporative soil layer could be overestimated [26].…”

Section: Discussionmentioning

confidence: 99%

“…However, the evaporation from the wet soil surface was estimated for the field monitored and the results were conveniently discussed. For a broad description of the soil evaporation model used in this work, the reader is referred to the FAO-56 Manual [6] and further modifications proposed by Torres and Calera [26]. The adaptation of this model using information derived from satellite images is described by Campos et al [13].…”

Section: Estimation Of Crop Transpirationmentioning

confidence: 99%

“…The relationship is generally established in terms of the basal crop coefficient or transpiration coefficient (Kcb) and the selected VI. Then, the soil evaporation coefficient (Ke) must be calculated by separately applying a daily soil water balance in the soil top layer, as proposed by Allen et al [6] and Torres and Calera [26] (Equation (2)):…”

Section: Estimation Of Crop Transpirationmentioning

confidence: 99%

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Irrigation Performance Assessment in Table Grape Using the Reflectance-Based Crop Coefficient

et al. 2017

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Abstract:In this paper, we present the results of our study on the operational application of the reflectance-based crop coefficient for assessing table grape irrigation requirements. The methodology was applied to provide irrigation advice and to assess the irrigation performance. The net irrigation water requirements (NIWR) simulated using the reflectance-based basal crop coefficient were provided to the farmer during the growing season and compared with the actual irrigation volumes applied. Two treatments were implemented in the field, increasing and reducing the irrigation doses by 25%, respectively, compared to the regular management. The experiment was carried out in a commercial orchard during three consecutive growing seasons in Northern Chile. The NIWR based on the model was approximately 900 mm per season for the orchard at tree maturity. The experimental results demonstrate that the regular irrigation applied covered only 76% of the NIWR for the whole season, and the analysis of monthly and weekly accumulated values indicates several periods of water shortage. The regular management system tended to underestimate the water requirements from October to January and overestimate the water requirements after harvest from February to April. The level of the deficit of water was quantified using such plant physiological parameters as stem water potential, vegetative development (coverage), and fruit productivity. The estimated NIWR was roughly covered in the treatment where the irrigation dose was increased, and the analyses of the crop production and fruit quality point to the relative advantage of this treatment. Finally, we conclude that the proposed approach allows the analysis of irrigation performance on the scale of commercial fields. These analytic capabilities are based on the well-demonstrated relationship of the crop evapotranspiration with the information provided by satellite images, and provide valuable information for irrigation management by identifying periods of water shortage and over-irrigation.

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Section: Discussionmentioning

confidence: 99%

Section: Estimation Of Crop Transpirationmentioning

confidence: 99%

Section: Estimation Of Crop Transpirationmentioning

confidence: 99%

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Irrigation Performance Assessment in Table Grape Using the Reflectance-Based Crop Coefficient

et al. 2017

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“…La simulación de la evaporación desde el suelo desnudo es uno de los aspectos que más desarrollo ha requerido desde la publicación del manual FAO56 (Allen, 2011;Torres and Calera, 2010). Por tanto, en muchos casos suele ser adecuado determinar la transpiración máxima de la cubierta mediante imágenes y aproximarse de forma específica al análisis de la componente evaporativa del suelo.…”

Section: 2-limitaciones a La Metodologíaunclassified

Predicción De Las Necesidades Hídricas Con Una Semana De Antelación Mediante Teledetección Y Meteorología en La Finca Experimental Del Center Para Cultivos De Maíz

Garrido-Rubio

González-Gómez

Alcázar

et al. 2015

XXXIII Congreso Nacional De Riegos

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ResumenDeterminar las necesidades hídricas que los cultivos demandarán a corto plazo juega un papel fundamental en la gestión de explotaciones agrícolas de regadío. De su precisión depende la obtención de mejores rendimientos productivos, económicos y medioambientales. La experiencia llevada a cabo en la finca experimental de la DGDRPF -CENTER del MAGRAMA, obtuvo la predicción de las necesidades hídricas con una semana de antelación durante todo el periodo de monitorización. Basados en la ecuación del coeficiente de cultivo único (Kc), de la metodología FAO56, se predijo la evapotranspiración del cultivo (ETc) en parcelas de maíz en regadío. Para ello, se emplearon técnicas meteorológicas que predijeron la evapotranspiración de referencia (ETo), y técnicas de teledetección basadas en secuencias temporales de índices de vegetación (IV) mediante las cuales se predijo el Kc. Los resultados obtenidos produjeron una ligera sobre estimación de la ETc a final de campaña (8%). Paralelamente, los riegos aplicados fueron validados externamente mediante el empleo de sondas de humedad. En resumen, la experiencia proporcionó resultados adecuados con un bajo número de recursos. Así, la programación del riego se realizó mediante la combinación de técnicas de teledetección y meteorológicas. 1-IntroducciónLa planificación del riego a la escala temporal de una semana es un aspecto de gran interés en el manejo de los cultivos por parte de los agricultores, pues permite la planificación de la aplicación de agua de riego de forma óptima teniendo en cuenta la disponibilidad de agua, del sistema de riego, y otros factores como la tarificación eléctrica, etc... Para ello, es necesario estimar las necesidades de agua del cultivo con una semana de antelación. Dado que las necesidades de agua se pueden calcular como el producto del Kc y la ETo, ambos parámetros deben ser estimados con el horizonte temporal señalado.

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“…The maximum value of the crop coefficient was set equal to 1.2 because of the contribution of evaporation from wetting intervals greater than 3 or 4 days [3], and the fraction cover values were derived from SAVI values using the relationship obtained by [35] for a row structured vineyard. Some authors have shown that under high evaporation conditions, the FAO-56 model overestimates soil evaporation at the beginning of the process [36,37]. We applied the correction proposed by [37] to improve the daily evaporation estimation of FAO-56 using the reduction of the readily evaporable water (REW) coefficient to limit stage I (evaporation occurs at the same rate as atmospheric demand) and the application of a factor (m) to reduce the K r coefficient in stage II (evaporation is lower than the atmospheric demand as a consequence of soil retention forces).…”

Section: Calculation Of Soil Evaporation Coefficientmentioning

confidence: 99%

Estimating Evapotranspiration of an Apple Orchard Using a Remote Sensing-Based Soil Water Balance

et al. 2016

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Abstract:The main goal of this research was to estimate the actual evapotranspiration (ET c ) of a drip-irrigated apple orchard located in the semi-arid region of Talca Valley (Chile) using a remote sensing-based soil water balance model. The methodology to estimate ET c is a modified version of the Food and Agriculture Organization of the United Nations (FAO) dual crop coefficient approach, in which the basal crop coefficient (K cb ) was derived from the soil adjusted vegetation index (SAVI) calculated from satellite images and incorporated into a daily soil water balance in the root zone. A linear relationship between the K cb and SAVI was developed for the apple orchard K cb = 1.82¨SAVI´0.07 (R 2 = 0.95). The methodology was applied during two growing seasons (2010-2011 and 2012-2013), and ET c was evaluated using latent heat fluxes (LE) from an eddy covariance system. The results indicate that the remote sensing-based soil water balance estimated ET c reasonably well over two growing seasons. The root mean square error (RMSE) between the measured and simulated ET c values during 2010-2011 and 2012-2013 were, respectively, 0.78 and 0.74 mm¨day´1, which mean a relative error of 25%. The index of agreement (d) values were, respectively, 0.73 and 0.90. In addition, the weekly ET c showed better agreement. The proposed methodology could be considered as a useful tool for scheduling irrigation and driving the estimation of water requirements over large areas for apple orchards.

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Bare soil evaporation under high evaporation demand: a proposed modification to the FAO-56 model

Cited by 48 publications

References 23 publications

Irrigation Performance Assessment in Table Grape Using the Reflectance-Based Crop Coefficient

Irrigation Performance Assessment in Table Grape Using the Reflectance-Based Crop Coefficient

Predicción De Las Necesidades Hídricas Con Una Semana De Antelación Mediante Teledetección Y Meteorología en La Finca Experimental Del Center Para Cultivos De Maíz

Estimating Evapotranspiration of an Apple Orchard Using a Remote Sensing-Based Soil Water Balance

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